Hierarchical comb brush architectures via sequential light-mediated controlled radical polymerizations

Narupai, Benjaporn; Poelma, Justin E.; Pester, Christian W.; McGrath, Alaina J.; Toumayan, Edward P.; Luo, Yingdong; Kramer, John W.; Clark, Paul G.; Ray, Paresh Chandra; Hawker, Craig J.

doi:10.1002/pola.28128

Cited by 26 publications

(23 citation statements)

References 64 publications

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“…Photocontrolled variants of living radical polymerizations, including atom-transfer radical-polymerization (ATRP), 2 organotellurium-mediated radical polymerizations (TERP), 3 and reversible addition–fragmentation chain transfer (RAFT) polymerizations, 4 have already demonstrated usefulness with a variety of monomers. This unprecedented command over polymeric architectures inspires numerous applications from the complex patterning of surfaces 5 to the synthesis of sequence-controlled polymers. 6 …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into the Photocontrolled Cationic Polymerization of Vinyl Ethers

et al. 2017

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The mechanism of the recently reported photocontrolled cationic polymerization of vinyl ethers was investigated using a variety of catalysts and chain-transfer agents (CTAs) as well as diverse spectroscopic and electrochemical analytical techniques. Our study revealed a complex activation step characterized by one-electron oxidation of the CTA. This oxidation is followed by mesolytic cleavage of the resulting radical cation species, which leads to the generation of a reactive cation–this species initiates the polymerization of the vinyl ether monomer–and a dithiocarbamate radical that is likely in equilibrium with the corresponding thiuram disulfide dimer. Reversible addition–fragmentation type degenerative chain transfer contributes to the narrow dispersities and control over chain growth observed under these conditions. Finally, the deactivation step is contingent upon the oxidation of the reduced photocatalyst by the dithiocarbamate radical concomitant with the production of a dithiocarbamate anion that caps the polymer chain end. The fine-tuning of the electronic properties and redox potentials of the photocatalyst in both the excited and the ground states is necessary to obtain a photocontrolled system rather than simply a photoinitiated system. The elucidation of the elementary steps of this process will aid the design of new catalytic systems and their real-world applications.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into the Photocontrolled Cationic Polymerization of Vinyl Ethers

et al. 2017

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“…By utilizing visible light, this method provides various advantages over the UV light-initiated approach, including on/off capabilities. Hawker and co-workers also demonstrated the growth of random copolymer brushes of methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) [76] and later developed light-mediated SI-ATRP by tethering the ATRP bromide initiator onto a SiO x surface. [1,55] From these surfaces, a variety of methacrylate polymer brushes were synthesized, including but not limited to: MMA, t-butyl methacrylate (tBuMA), poly(ethylene glycol) methacrylate (PEGMA), and trifluoroethyl methacrylate (TFEMA).…”

Section: Surface-initiated Atom Transfer Radical Polymerization (Si-amentioning

confidence: 99%

Surface Engineering with Polymer Brush Photolithography

Fromel

Pester

2020

Macromol. Rapid Commun.

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Surface‐tethered macromolecules, or polymer brushes, offer a unique platform for coating surfaces for a wide variety of applications. Surface‐initiated polymerization (SI‐P), through which polymer brushes can be grown directly from an initiator‐functionalized surface, offers a facile, highly customizable approach that is synergistic with photolithography. Using a variety of photolithography devices and SI‐Ps, complex polymer brush architectures can be fabricated with great spatial and temporal control. This article not only addresses techniques, advancements, applications, and possible future directions within the field of polymer brush photolithography, but it also provides resources to assist the reader in selecting the polymerization technique and photolithography device most conducive to a given endeavor.

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“…Subsequent controlled polymerization provides defined polymer layer thickness, grafting density, and chemical composition, with the covalent surface-tether making these surfaces robust and chemically resistant. [5] Recently, organic catalysts, [6] external regulation for patterning, [4,[6][7][8][9][10][11][12][13][14] and increased oxygen tolerance [6,9,13,15,16] have been introduced to allow complex patterning on the benchtop. These improvements now offer more intriguing possibilities for engineering of layered and patterned polymer thin films than ever before.…”

Section: The Reproducibility Of Polymer Brush Synthesis Via Surface-imentioning

confidence: 99%

Comparison of Long‐Term Stability of Initiating Monolayers in Surface‐Initiated Controlled Radical Polymerizations

Fromel

Ranaweera

et al. 2020

Macromol. Rapid Commun.

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The reproducibility of polymer brush synthesis via surface‐initiated controlled radical polymerization is interrogated. Experiments compare the stability of initiating monolayers for surface‐initiated (SI) reversible addition‐fragmentation chain transfer polymerization (SI‐RAFT) and SI atom transfer radical polymerization (SI‐ATRP). Initiator‐functionalized substrates are stored under various conditions and grafting densities of the resulting polymer brush films are determined via in situ ellipsometry. Decomposition of one of the examined SI‐RAFT initiators results in limited reproducibility for polymer brush surface modification. In contrast, initiators for SI‐ATRP show excellent stability and reproducibility. While both techniques bring inherent benefits and limitations, the described findings will help scientists choose the most efficient technique for their goals in chemical and topographical surface modification.

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Hierarchical comb brush architectures via sequential light-mediated controlled radical polymerizations

Cited by 26 publications

References 64 publications

Mechanistic Insight into the Photocontrolled Cationic Polymerization of Vinyl Ethers

Mechanistic Insight into the Photocontrolled Cationic Polymerization of Vinyl Ethers

Surface Engineering with Polymer Brush Photolithography

Comparison of Long‐Term Stability of Initiating Monolayers in Surface‐Initiated Controlled Radical Polymerizations

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